A display unit is manufactured by bonding a polarizing film that is an optical functional film generally called a polarizing plate to each of an upper surface (viewing side) and a lower surface (backlight side) of a panel formed of a liquid crystal layer, which is interposed between rectangular glass substrates and on which a transparent electrode, a color filter, and the like, are disposed, in a form of sheet pieces.
In order to continuously manufacture a display unit by using a roll-type optical film including a polarizing film including an adhesive layer, and a release film adhering to the adhesive layer so as to be peeled off, continuous slit lines are formed in the supplied optical film, and polarizing film sheet pieces formed by the slit lines are peeled from the release film and bonded to the panel.
An important technical object in manufacturing the display unit is to confirm a defect of the manufactured display unit in advance and prevent an incurrence of a defective product. Accordingly, it is possible to remarkably improve the yield of the manufacturing the display unit. A considerable number of defects are mainly caused by a defect existing in the polarizing film included in an optical film laminated structure, and it is difficult to provide an optical film laminated structure in a state where the defects included in the respective laminated films are completely removed. According to the investigation of all of a polarizer forming the polarizing film, a protective film laminated on the polarizer, and the adhesive layer formed in the polarizing film, it has been revealed that various forms of 20 to 200 defects per 1,000 m of the polarizing film, which includes defects existing in a PVA film itself of the polarizer, defects generated when the protective film is laminated on the polarizer, and defects generated in the adhesive layer of the polarizing film, are distributed. This represents that it is currently extremely difficult to manufacture the polarizing film having no defect.
In order to improve a yield of the manufacturing the display unit, sheet pieces (hereinafter, referred to as the normal sheet piece) of normal products are cut by adequately avoiding an area including a defect in the optical film laminated structure, and the sheet pieces are bonded to the panel. Further, the area including the defect in the optical film laminated structure is a sheet piece (hereinafter, referred to as the defective sheet piece) of a defective product, and the corresponding area is cut, but is processed to be excluded in a subsequent process.
Accordingly, there is required a method of continuously manufacturing a display unit, which is capable of bonding only the sheet piece determined as the normal sheet piece to the panel even without a stop of the supply of the optical film by providing a means, which prevents the sheet piece determined as the defective sheet piece from being bonded to the panel, between the normal sheet piece and the defective sheet piece of the polarizing film, which are sequentially formed on the release film in a cut state.
Korean Patent Application Laid-Open No. 10-2015-0121004 (hereinafter, Patent Document 1) suggests a system for producing an optical display device. The Patent Document confirms a position of a mark assigned to an optical film and determines a forming position of a cutting line based on the confirmed position of the mark, so that it is difficult to apply the Patent Document to a process of carrying the optical film in the unit of a pitch.